// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_APP_LIST_SEARCH_HISTORY_DATA_H_
#define UI_APP_LIST_SEARCH_HISTORY_DATA_H_

#include <stddef.h>

#include <deque>
#include <map>
#include <string>

#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/time/time.h"
#include "ui/app_list/app_list_export.h"
#include "ui/app_list/search/history_types.h"

namespace app_list {

class HistoryDataObserver;
class HistoryDataStore;

// HistoryData stores the associations of the user typed queries and launched
// search result id. There are two types of association: primary and secondary.
// Primary is a 1-to-1 mapping between the query and result id. Secondary
// is a 1-to-many mapping and only kept the last 5 to limit the data size.
// If an association is added for the first time, it is added as a primary
// association. Further associations added to the same query are added as
// secondary. However, if a secondary association is added twice in a row, it
// is promoted to primary and the current primary mapping is demoted into
// secondary.
class APP_LIST_EXPORT HistoryData : public base::SupportsWeakPtr<HistoryData> {
public:
    typedef std::deque<std::string> SecondaryDeque;

    // Defines data to be associated with a query.
    struct APP_LIST_EXPORT Data {
        Data();
        ~Data();

        // Primary result associated with the query.
        std::string primary;

        // Secondary results associated with the query from oldest to latest.
        SecondaryDeque secondary;

        // Last update time.
        base::Time update_time;
    };
    typedef std::map<std::string, Data> Associations;

    // Constructor of HistoryData. |store| is the storage to persist the data.
    // |max_primary| is the maximum number of the most recent primary associations
    // to keep. |max_secondary| is the maximum number of secondary associations to
    // keep.
    HistoryData(HistoryDataStore* store,
        size_t max_primary,
        size_t max_secondary);
    ~HistoryData();

    // Adds an association.
    void Add(const std::string& query, const std::string& result_id);

    // Gets all known search results that were launched using the given |query|
    // or the queries that |query| is a prefix of.
    scoped_ptr<KnownResults> GetKnownResults(const std::string& query) const;

    void AddObserver(HistoryDataObserver* observer);
    void RemoveObserver(HistoryDataObserver* observer);

    const Associations& associations() const { return associations_; }

private:
    // Invoked from |store| with loaded data.
    void OnStoreLoaded(scoped_ptr<Associations> loaded_data);

    // Trims the data to keep the most recent |max_primary_| queries.
    void TrimEntries();

    HistoryDataStore* store_; // Not owned.
    const size_t max_primary_;
    const size_t max_secondary_;
    base::ObserverList<HistoryDataObserver, true> observers_;

    Associations associations_;

    DISALLOW_COPY_AND_ASSIGN(HistoryData);
};

} // namespace app_list

#endif // UI_APP_LIST_SEARCH_HISTORY_DATA_H_
